1. Technical Field
The present disclosure relates to memory devices. In particular, the present disclosure relates to a memory device and method for detecting bit errors therein.
2. Discussion of Related Art
Memory devices are used for storing and retrieving data. Memory devices are largely classified into random access memories (RAMs) and read-only memories (ROMs). RAMs are volatile memory devices that lose their stored data when a power supply is turned off. ROMs are nonvolatile memory devices that retain data even without power supply. RAMs include dynamic RAMs and static RAMs. ROMs include programmable ROMs (PROMs), erasable PROMs (EPROMs), electrically EPROMs (EEPROMs), and flash memories.
The flash memories are widely employed in mobile communication terminals, portable media players, digital cameras, mobile storage media, and so forth. In using the flash memories for storage media, data integrity needs to be assured. However, data stored on the flash memory devices typically includes bit errors. With their inherent property as memory devices, the flash memories (or a flash memory system) need to have functions for detecting and correcting bit errors therein. Flash memories employ error correction code (ECC) circuits for detecting and correcting bit errors therein.
The ECC circuits used in the flash memory device. The ECC circuits are designed to correct m-bit errors (for example, 1-bit error) and to detect n-bit errors (for example, 2-bit errors). Any more than n-bit errors (for example, 2-bit errors) may not be detected in the flash memory. This limit on the number of detectable error bits degrades the reliability of the flash memory device.